http://www.wolframalpha.com/input/?i=USA+debt+vs+gdp http://www.wolframalpha.com/input/?i=USA+debt+vs+gdp In the graph, the debt is clearly starting to go para

http://www.wolframalpha.com/input/?i=USA+debt+vs+gdp http://www.wolframalpha.com/input/?i=USA+debt+vs+gdp In the graph, the debt is clearly starting to go parabolic in the last decade while the gdp stays linear. That's the problem right there viz. no cx can always beat a kx^2 for any c,k 'cause beyond x=(c/k), the kx^2 will win. morover the c is realtively static for a developed first world nation - you are not going to see USA growing at 9 and 10% like India/China. It'll be like 2% and 3% best case cause the US economy is so large growing it even 1% is a monumental task. Whereas the k, once it picks up steam, actually gets really large really fast. Your interest piles up and you can't pay so you borrow more so the rate goes up on you so the interest piles up even faster and repeat...